I would think that the easiest way to use Ubuntu's repositories is to use
Ubuntu. Besides the likely breakage that's going to occur from trying to add
these repositories to Trisquel, you're going to end up pulling all of your
software from the Ubuntu repositories, anyway. What would you be achieving?
> want repositories that always have the very latest of each of the creative
software I use
None of Ubuntu's repositories do this. All Ubuntu releases are stable; for
the most part, only security updates pushed once a release is made. So unless
a vulnerability in the GIMP is found, it will be the same version for the
entirety of the release's life span.
A distro that actually keeps the latest versions of programs in the
repository is called "rolling-release". This setup is highly prone to
breakage, and so should only be used if you know what you're doing. Parabola
is the example of such a distro which is 100% libre software. Debian Sid
(unstable) is also rolling-release.
